The current fitting approach adopted for cochlear implant (CI) users falls along the lines of "one-size-fits-all", in that it is assumed that the initial fitting in the clinic should work equally well in all listening environments. Speech coding algorithms and associated parameters (e.g., compression function) are fixed and are not optimized in any way by either the patient or clinician for different listening situations (e.g., quiet, music, noise). The present study addresses this major limitation with the use of a portable research speech processor that allows users to: (a) change MAP parameters based on two different outcome measures (subjective quality ratings and consonant intelligibility) (b) customize the MAP to different listening situations for maximum benefit, and (c) collect feedback and allow the recording of real acoustic signals for further analysis. In this study, unilateral, bilateral and bimodal users will participate in double-blind field trials to assess the true benefit of a speech processor that can be easily customized by the users to fit their needs based on subjective quality ratings or speech intelligibility measures. The overarching hypothesis of this project is that maximum benefit, both in terms of subjective quality and intelligibility, can be obtained when the cochlear implant devices are customized (by the users) to the various listening situations. The outcomes of the field studies will tell us about the difficulties experienced by CI users in real-world situations as well as the value and additional benefit of customizing speech coding algorithms to different environments, all based on feedback from CI users. Such feedback and user interaction can not be gathered using existing commercial processors, yet it is critically needed to move the field forward. PUBLIC HEALTH RELEVANCE: The outcomes of this work can greatly benefit the overall quality of life for a large number of cochlear implant users. Cochlear implant users who are able to communicate effectively in noisy environments have greater opportunity for integration into mainstream education, increase their productivity at home or work and contribute more in the nation's economic growth and competitiveness.